Sprinkler systems for turf irrigation are well known. Typical systems include a plurality of valves and sprinkler heads in fluid communication with a water source, and a centralized controller connected to the water valves. At appropriate times the controller opens the normally closed valves to allow water to flow from the water source to the sprinkler heads. Water then issues from the sprinkler heads in predetermined fashion.
There are many different types of sprinkler heads, including above-the-ground heads and “pop-up” heads. Pop-up sprinklers, though generally more complicated and expensive than other types of sprinklers, are thought to be superior. There are several reasons for this. For example, a pop-up sprinkler's nozzle opening is typically covered when the sprinkler is not in use and is therefore less likely to be partially or completely plugged by debris or insects. Also, when not being used, a pop-up sprinkler is entirely below the surface and out of the way.
The typical pop-up sprinkler head includes a stationary body and a “riser” which extends vertically upward, or “pops up,” when water is allowed to flow to the sprinkler. The riser is in the nature of a hollow tube which supports a nozzle at its upper end. When the normally-closed valve associated with a sprinkler opens to allow water to flow to the sprinkler, two things happen: (i) water pressure pushes against the riser to move it from its retracted to its fully extended position, and (ii) water flows axially upward through the riser, and the nozzle receives the axial flow from the riser and turns it radially to create a radial stream. A spring or other type of resilient element is interposed between the body and the riser to continuously urge the riser toward its retracted, subsurface, position, so that when water pressure is removed the riser assembly will immediately return to its retracted position.
The riser assembly of a pop-up or above-the-ground sprinkler head can remain rotationally stationary or can include a portion that rotates in continuous or oscillatory fashion to water a circular or partly circular area, respectively. More specifically, the riser assembly of the typical rotary sprinkler includes a first portion (e.g. the riser), which does not rotate, and a second portion, (e.g., the nozzle assembly) which rotates relative to the first (non-rotating) portion.
The rotating portion of a rotary sprinkler riser typically carries a nozzle at its uppermost end. The nozzle throws at least one water stream outwardly to one side of the nozzle assembly. As the nozzle assembly rotates, the water stream travels or sweeps over the ground, creating a watering arc.
One drawback with this type of sprinkler nozzle is uneven coverage and distribution of water. Typically, if water is thrown in a coherent stream at some trajectory relative to the surface to be watered, the stream will tend to water a doughnut shaped ring around the sprinkler with little water being deposited close to the sprinkler. This is obviously a disadvantage since the vegetation closest to the sprinkler will be under-watered. One way of compensating for this could be to increase the length of time the sprinkler is allowed to run. However, increasing water usage to ensure proper watering of vegetation closest to the sprinkler also means that vegetation further away from the sprinkler (i.e., in the outer radial portions of the watering pattern) will then be over-watered.
Another drawback associated with conventional sprinkler nozzle designs involves water turbulence. For example, as water flows through the fluid passageway of a nozzle, it impacts against the walls or surfaces of the passageway. Water flowing through the passageway and impacting against the surface often changes the stream of water exiting the nozzle from a substantially droplet form into a spray or mist form. As such, water thrown in a spray or mist form is easily blown by the wind and, thereby, produces inaccurate and uneven irrigation of the target area.
To compensate for uneven water distribution, sprinkler systems must be arranged so that the spray patterns of each sprinkler overlap with one another. Known in the industry as head-to-head coverage or head-to-head spacing, this type of sprinkler arrangement ensures overlap of watered areas to produce uniform water application. However, this arrangement tends to be rather costly and labor intensive at the initial set-up due to the quantity of sprinkler heads and accessory components required. Further, as with any system, the greater the number of components, the greater the cost to maintain such a system.
In view of the above, there is a need for an improved sprinkler nozzle for both above-the ground and pop-up rotary sprinkler systems. In particular, it is desirable that the nozzle applies water in a uniform pattern that provides even coverage and distribution of water. In addition, the nozzle should also be configured to include a broad throw pattern with even water distribution over the entire area. Furthermore, it is desirable that the nozzle reduce water turbulence in order to deliver optimum water-efficient coverage over the irrigation surface.